libavcodec/sipr.c

   1 /*
   2  * SIPR / ACELP.NET decoder
   3  *
   4  * Copyright (c) 2008 Vladimir Voroshilov
   5  * Copyright (c) 2009 Vitor Sessak
   6  *
   7  * This file is part of FFmpeg.
   8  *
   9  * FFmpeg is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public
  11  * License as published by the Free Software Foundation; either
  12  * version 2.1 of the License, or (at your option) any later version.
  13  *
  14  * FFmpeg is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public
  20  * License along with FFmpeg; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  22  */
  23
  24 #include <math.h>
  25 #include <stdint.h>
  26 #include <string.h>
  27
  28 #include "libavutil/channel_layout.h"
  29 #include "libavutil/float_dsp.h"
  30 #include "libavutil/mathematics.h"
  31
  32 #define BITSTREAM_READER_LE
  33 #include "avcodec.h"
  34 #include "codec_internal.h"
  35 #include "get_bits.h"
  36 #include "internal.h"
  37 #include "lsp.h"
  38 #include "acelp_vectors.h"
  39 #include "acelp_pitch_delay.h"
  40 #include "acelp_filters.h"
  41 #include "celp_filters.h"
  42
  43 #define MAX_SUBFRAME_COUNT   5
  44
  45 #include "sipr.h"
  46 #include "siprdata.h"
  47
  48 typedef struct SiprModeParam {
  49     const char *mode_name;
  50     uint16_t bits_per_frame;
  51     uint8_t subframe_count;
  52     uint8_t frames_per_packet;
  53     float pitch_sharp_factor;
  54
  55     /* bitstream parameters */
  56     uint8_t number_of_fc_indexes;
  57     uint8_t ma_predictor_bits;  ///< size in bits of the switched MA predictor
  58
  59     /** size in bits of the i-th stage vector of quantizer */
  60     uint8_t vq_indexes_bits[5];
  61
  62     /** size in bits of the adaptive-codebook index for every subframe */
  63     uint8_t pitch_delay_bits[5];
  64
  65     uint8_t gp_index_bits;
  66     uint8_t fc_index_bits[10]; ///< size in bits of the fixed codebook indexes
  67     uint8_t gc_index_bits;     ///< size in bits of the gain  codebook indexes
  68 } SiprModeParam;
  69
  70 static const SiprModeParam modes[MODE_COUNT] = {
  71     [MODE_16k] = {
  72         .mode_name          = "16k",
  73         .bits_per_frame     = 160,
  74         .subframe_count     = SUBFRAME_COUNT_16k,
  75         .frames_per_packet  = 1,
  76         .pitch_sharp_factor = 0.00,
  77
  78         .number_of_fc_indexes = 10,
  79         .ma_predictor_bits    = 1,
  80         .vq_indexes_bits      = {7, 8, 7, 7, 7},
  81         .pitch_delay_bits     = {9, 6},
  82         .gp_index_bits        = 4,
  83         .fc_index_bits        = {4, 5, 4, 5, 4, 5, 4, 5, 4, 5},
  84         .gc_index_bits        = 5
  85     },
  86
  87     [MODE_8k5] = {
  88         .mode_name          = "8k5",
  89         .bits_per_frame     = 152,
  90         .subframe_count     = 3,
  91         .frames_per_packet  = 1,
  92         .pitch_sharp_factor = 0.8,
  93
  94         .number_of_fc_indexes = 3,
  95         .ma_predictor_bits    = 0,
  96         .vq_indexes_bits      = {6, 7, 7, 7, 5},
  97         .pitch_delay_bits     = {8, 5, 5},
  98         .gp_index_bits        = 0,
  99         .fc_index_bits        = {9, 9, 9},
 100         .gc_index_bits        = 7
 101     },
 102
 103     [MODE_6k5] = {
 104         .mode_name          = "6k5",
 105         .bits_per_frame     = 232,
 106         .subframe_count     = 3,
 107         .frames_per_packet  = 2,
 108         .pitch_sharp_factor = 0.8,
 109
 110         .number_of_fc_indexes = 3,
 111         .ma_predictor_bits    = 0,
 112         .vq_indexes_bits      = {6, 7, 7, 7, 5},
 113         .pitch_delay_bits     = {8, 5, 5},
 114         .gp_index_bits        = 0,
 115         .fc_index_bits        = {5, 5, 5},
 116         .gc_index_bits        = 7
 117     },
 118
 119     [MODE_5k0] = {
 120         .mode_name          = "5k0",
 121         .bits_per_frame     = 296,
 122         .subframe_count     = 5,
 123         .frames_per_packet  = 2,
 124         .pitch_sharp_factor = 0.85,
 125
 126         .number_of_fc_indexes = 1,
 127         .ma_predictor_bits    = 0,
 128         .vq_indexes_bits      = {6, 7, 7, 7, 5},
 129         .pitch_delay_bits     = {8, 5, 8, 5, 5},
 130         .gp_index_bits        = 0,
 131         .fc_index_bits        = {10},
 132         .gc_index_bits        = 7
 133     }
 134 };
 135
 136 const float ff_pow_0_5[] = {
 137     1.0/(1 <<  1), 1.0/(1 <<  2), 1.0/(1 <<  3), 1.0/(1 <<  4),
 138     1.0/(1 <<  5), 1.0/(1 <<  6), 1.0/(1 <<  7), 1.0/(1 <<  8),
 139     1.0/(1 <<  9), 1.0/(1 << 10), 1.0/(1 << 11), 1.0/(1 << 12),
 140     1.0/(1 << 13), 1.0/(1 << 14), 1.0/(1 << 15), 1.0/(1 << 16)
 141 };
 142
 143 static void dequant(float *out, const int *idx, const float * const cbs[])
 144 {
 145     int i;
 146     int stride  = 2;
 147     int num_vec = 5;
 148
 149     for (i = 0; i < num_vec; i++)
 150         memcpy(out + stride*i, cbs[i] + stride*idx[i], stride*sizeof(float));
 151
 152 }
 153
 154 static void lsf_decode_fp(float *lsfnew, float *lsf_history,
 155                           const SiprParameters *parm)
 156 {
 157     int i;
 158     float lsf_tmp[LP_FILTER_ORDER];
 159
 160     dequant(lsf_tmp, parm->vq_indexes, lsf_codebooks);
 161
 162     for (i = 0; i < LP_FILTER_ORDER; i++)
 163         lsfnew[i] = lsf_history[i] * 0.33 + lsf_tmp[i] + mean_lsf[i];
 164
 165     ff_sort_nearly_sorted_floats(lsfnew, LP_FILTER_ORDER - 1);
 166
 167     /* Note that a minimum distance is not enforced between the last value and
 168        the previous one, contrary to what is done in ff_acelp_reorder_lsf() */
 169     ff_set_min_dist_lsf(lsfnew, LSFQ_DIFF_MIN, LP_FILTER_ORDER - 1);
 170     lsfnew[9] = FFMIN(lsfnew[LP_FILTER_ORDER - 1], 1.3 * M_PI);
 171
 172     memcpy(lsf_history, lsf_tmp, LP_FILTER_ORDER * sizeof(*lsf_history));
 173
 174     for (i = 0; i < LP_FILTER_ORDER - 1; i++)
 175         lsfnew[i] = cos(lsfnew[i]);
 176     lsfnew[LP_FILTER_ORDER - 1] *= 6.153848 / M_PI;
 177 }
 178
 179 /** Apply pitch lag to the fixed vector (AMR section 6.1.2). */
 180 static void pitch_sharpening(int pitch_lag_int, float beta,
 181                              float *fixed_vector)
 182 {
 183     int i;
 184
 185     for (i = pitch_lag_int; i < SUBFR_SIZE; i++)
 186         fixed_vector[i] += beta * fixed_vector[i - pitch_lag_int];
 187 }
 188
 189 /**
 190  * Extract decoding parameters from the input bitstream.
 191  * @param parms          parameters structure
 192  * @param pgb            pointer to initialized GetBitContext structure
 193  */
 194 static void decode_parameters(SiprParameters* parms, GetBitContext *pgb,
 195                               const SiprModeParam *p)
 196 {
 197     int i, j;
 198
 199     if (p->ma_predictor_bits)
 200         parms->ma_pred_switch       = get_bits(pgb, p->ma_predictor_bits);
 201
 202     for (i = 0; i < 5; i++)
 203         parms->vq_indexes[i]        = get_bits(pgb, p->vq_indexes_bits[i]);
 204
 205     for (i = 0; i < p->subframe_count; i++) {
 206         parms->pitch_delay[i]       = get_bits(pgb, p->pitch_delay_bits[i]);
 207         if (p->gp_index_bits)
 208             parms->gp_index[i]      = get_bits(pgb, p->gp_index_bits);
 209
 210         for (j = 0; j < p->number_of_fc_indexes; j++)
 211             parms->fc_indexes[i][j] = get_bits(pgb, p->fc_index_bits[j]);
 212
 213         parms->gc_index[i]          = get_bits(pgb, p->gc_index_bits);
 214     }
 215 }
 216
 217 static void sipr_decode_lp(float *lsfnew, const float *lsfold, float *Az,
 218                            int num_subfr)
 219 {
 220     double lsfint[LP_FILTER_ORDER];
 221     int i,j;
 222     float t, t0 = 1.0 / num_subfr;
 223
 224     t = t0 * 0.5;
 225     for (i = 0; i < num_subfr; i++) {
 226         for (j = 0; j < LP_FILTER_ORDER; j++)
 227             lsfint[j] = lsfold[j] * (1 - t) + t * lsfnew[j];
 228
 229         ff_amrwb_lsp2lpc(lsfint, Az, LP_FILTER_ORDER);
 230         Az += LP_FILTER_ORDER;
 231         t += t0;
 232     }
 233 }
 234
 235 /**
 236  * Evaluate the adaptive impulse response.
 237  */
 238 static void eval_ir(const float *Az, int pitch_lag, float *freq,
 239                     float pitch_sharp_factor)
 240 {
 241     float tmp1[SUBFR_SIZE+1], tmp2[LP_FILTER_ORDER+1];
 242     int i;
 243
 244     tmp1[0] = 1.0;
 245     for (i = 0; i < LP_FILTER_ORDER; i++) {
 246         tmp1[i+1] = Az[i] * ff_pow_0_55[i];
 247         tmp2[i  ] = Az[i] * ff_pow_0_7 [i];
 248     }
 249     memset(tmp1 + 11, 0, 37 * sizeof(float));
 250
 251     ff_celp_lp_synthesis_filterf(freq, tmp2, tmp1, SUBFR_SIZE,
 252                                  LP_FILTER_ORDER);
 253
 254     pitch_sharpening(pitch_lag, pitch_sharp_factor, freq);
 255 }
 256
 257 /**
 258  * Evaluate the convolution of a vector with a sparse vector.
 259  */
 260 static void convolute_with_sparse(float *out, const AMRFixed *pulses,
 261                                   const float *shape, int length)
 262 {
 263     int i, j;
 264
 265     memset(out, 0, length*sizeof(float));
 266     for (i = 0; i < pulses->n; i++)
 267         for (j = pulses->x[i]; j < length; j++)
 268             out[j] += pulses->y[i] * shape[j - pulses->x[i]];
 269 }
 270
 271 /**
 272  * Apply postfilter, very similar to AMR one.
 273  */
 274 static void postfilter_5k0(SiprContext *ctx, const float *lpc, float *samples)
 275 {
 276     float buf[SUBFR_SIZE + LP_FILTER_ORDER];
 277     float *pole_out = buf + LP_FILTER_ORDER;
 278     float lpc_n[LP_FILTER_ORDER];
 279     float lpc_d[LP_FILTER_ORDER];
 280     int i;
 281
 282     for (i = 0; i < LP_FILTER_ORDER; i++) {
 283         lpc_d[i] = lpc[i] * ff_pow_0_75[i];
 284         lpc_n[i] = lpc[i] * ff_pow_0_5 [i];
 285     };
 286
 287     memcpy(pole_out - LP_FILTER_ORDER, ctx->postfilter_mem,
 288            LP_FILTER_ORDER*sizeof(float));
 289
 290     ff_celp_lp_synthesis_filterf(pole_out, lpc_d, samples, SUBFR_SIZE,
 291                                  LP_FILTER_ORDER);
 292
 293     memcpy(ctx->postfilter_mem, pole_out + SUBFR_SIZE - LP_FILTER_ORDER,
 294            LP_FILTER_ORDER*sizeof(float));
 295
 296     ff_tilt_compensation(&ctx->tilt_mem, 0.4, pole_out, SUBFR_SIZE);
 297
 298     memcpy(pole_out - LP_FILTER_ORDER, ctx->postfilter_mem5k0,
 299            LP_FILTER_ORDER*sizeof(*pole_out));
 300
 301     memcpy(ctx->postfilter_mem5k0, pole_out + SUBFR_SIZE - LP_FILTER_ORDER,
 302            LP_FILTER_ORDER*sizeof(*pole_out));
 303
 304     ff_celp_lp_zero_synthesis_filterf(samples, lpc_n, pole_out, SUBFR_SIZE,
 305                                       LP_FILTER_ORDER);
 306
 307 }
 308
 309 static void decode_fixed_sparse(AMRFixed *fixed_sparse, const int16_t *pulses,
 310                                 SiprMode mode, int low_gain)
 311 {
 312     int i;
 313
 314     switch (mode) {
 315     case MODE_6k5:
 316         for (i = 0; i < 3; i++) {
 317             fixed_sparse->x[i] = 3 * (pulses[i] & 0xf) + i;
 318             fixed_sparse->y[i] = pulses[i] & 0x10 ? -1 : 1;
 319         }
 320         fixed_sparse->n = 3;
 321         break;
 322     case MODE_8k5:
 323         for (i = 0; i < 3; i++) {
 324             fixed_sparse->x[2*i    ] = 3 * ((pulses[i] >> 4) & 0xf) + i;
 325             fixed_sparse->x[2*i + 1] = 3 * ( pulses[i]       & 0xf) + i;
 326
 327             fixed_sparse->y[2*i    ] = (pulses[i] & 0x100) ? -1.0: 1.0;
 328
 329             fixed_sparse->y[2*i + 1] =
 330                 (fixed_sparse->x[2*i + 1] < fixed_sparse->x[2*i]) ?
 331                 -fixed_sparse->y[2*i    ] : fixed_sparse->y[2*i];
 332         }
 333
 334         fixed_sparse->n = 6;
 335         break;
 336     case MODE_5k0:
 337     default:
 338         if (low_gain) {
 339             int offset = (pulses[0] & 0x200) ? 2 : 0;
 340             int val = pulses[0];
 341
 342             for (i = 0; i < 3; i++) {
 343                 int index = (val & 0x7) * 6 + 4 - i*2;
 344
 345                 fixed_sparse->y[i] = (offset + index) & 0x3 ? -1 : 1;
 346                 fixed_sparse->x[i] = index;
 347
 348                 val >>= 3;
 349             }
 350             fixed_sparse->n = 3;
 351         } else {
 352             int pulse_subset = (pulses[0] >> 8) & 1;
 353
 354             fixed_sparse->x[0] = ((pulses[0] >> 4) & 15) * 3 + pulse_subset;
 355             fixed_sparse->x[1] = ( pulses[0]       & 15) * 3 + pulse_subset + 1;
 356
 357             fixed_sparse->y[0] = pulses[0] & 0x200 ? -1 : 1;
 358             fixed_sparse->y[1] = -fixed_sparse->y[0];
 359             fixed_sparse->n = 2;
 360         }
 361         break;
 362     }
 363 }
 364
 365 static void decode_frame(SiprContext *ctx, SiprParameters *params,
 366                          float *out_data)
 367 {
 368     int i, j;
 369     int subframe_count = modes[ctx->mode].subframe_count;
 370     int frame_size = subframe_count * SUBFR_SIZE;
 371     float Az[LP_FILTER_ORDER * MAX_SUBFRAME_COUNT];
 372     float *excitation;
 373     float ir_buf[SUBFR_SIZE + LP_FILTER_ORDER];
 374     float lsf_new[LP_FILTER_ORDER];
 375     float *impulse_response = ir_buf + LP_FILTER_ORDER;
 376     float *synth = ctx->synth_buf + 16; // 16 instead of LP_FILTER_ORDER for
 377                                         // memory alignment
 378     int t0_first = 0;
 379     AMRFixed fixed_cb;
 380
 381     memset(ir_buf, 0, LP_FILTER_ORDER * sizeof(float));
 382     lsf_decode_fp(lsf_new, ctx->lsf_history, params);
 383
 384     sipr_decode_lp(lsf_new, ctx->lsp_history, Az, subframe_count);
 385
 386     memcpy(ctx->lsp_history, lsf_new, LP_FILTER_ORDER * sizeof(float));
 387
 388     excitation = ctx->excitation + PITCH_DELAY_MAX + L_INTERPOL;
 389
 390     for (i = 0; i < subframe_count; i++) {
 391         float *pAz = Az + i*LP_FILTER_ORDER;
 392         float fixed_vector[SUBFR_SIZE];
 393         int T0,T0_frac;
 394         float pitch_gain, gain_code, avg_energy;
 395
 396         ff_decode_pitch_lag(&T0, &T0_frac, params->pitch_delay[i], t0_first, i,
 397                             ctx->mode == MODE_5k0, 6);
 398
 399         if (i == 0 || (i == 2 && ctx->mode == MODE_5k0))
 400             t0_first = T0;
 401
 402         ff_acelp_interpolatef(excitation, excitation - T0 + (T0_frac <= 0),
 403                               ff_b60_sinc, 6,
 404                               2 * ((2 + T0_frac)%3 + 1), LP_FILTER_ORDER,
 405                               SUBFR_SIZE);
 406
 407         decode_fixed_sparse(&fixed_cb, params->fc_indexes[i], ctx->mode,
 408                             ctx->past_pitch_gain < 0.8);
 409
 410         eval_ir(pAz, T0, impulse_response, modes[ctx->mode].pitch_sharp_factor);
 411
 412         convolute_with_sparse(fixed_vector, &fixed_cb, impulse_response,
 413                               SUBFR_SIZE);
 414
 415         avg_energy = (0.01 + avpriv_scalarproduct_float_c(fixed_vector,
 416                                                           fixed_vector,
 417                                                           SUBFR_SIZE)) /
 418                      SUBFR_SIZE;
 419
 420         ctx->past_pitch_gain = pitch_gain = gain_cb[params->gc_index[i]][0];
 421
 422         gain_code = ff_amr_set_fixed_gain(gain_cb[params->gc_index[i]][1],
 423                                           avg_energy, ctx->energy_history,
 424                                           34 - 15.0/(0.05*M_LN10/M_LN2),
 425                                           pred);
 426
 427         ff_weighted_vector_sumf(excitation, excitation, fixed_vector,
 428                                 pitch_gain, gain_code, SUBFR_SIZE);
 429
 430         pitch_gain *= 0.5 * pitch_gain;
 431         pitch_gain = FFMIN(pitch_gain, 0.4);
 432
 433         ctx->gain_mem = 0.7 * ctx->gain_mem + 0.3 * pitch_gain;
 434         ctx->gain_mem = FFMIN(ctx->gain_mem, pitch_gain);
 435         gain_code *= ctx->gain_mem;
 436
 437         for (j = 0; j < SUBFR_SIZE; j++)
 438             fixed_vector[j] = excitation[j] - gain_code * fixed_vector[j];
 439
 440         if (ctx->mode == MODE_5k0) {
 441             postfilter_5k0(ctx, pAz, fixed_vector);
 442
 443             ff_celp_lp_synthesis_filterf(ctx->postfilter_syn5k0 + LP_FILTER_ORDER + i*SUBFR_SIZE,
 444                                          pAz, excitation, SUBFR_SIZE,
 445                                          LP_FILTER_ORDER);
 446         }
 447
 448         ff_celp_lp_synthesis_filterf(synth + i*SUBFR_SIZE, pAz, fixed_vector,
 449                                      SUBFR_SIZE, LP_FILTER_ORDER);
 450
 451         excitation += SUBFR_SIZE;
 452     }
 453
 454     memcpy(synth - LP_FILTER_ORDER, synth + frame_size - LP_FILTER_ORDER,
 455            LP_FILTER_ORDER * sizeof(float));
 456
 457     if (ctx->mode == MODE_5k0) {
 458         for (i = 0; i < subframe_count; i++) {
 459             float energy = avpriv_scalarproduct_float_c(ctx->postfilter_syn5k0 + LP_FILTER_ORDER + i * SUBFR_SIZE,
 460                                                         ctx->postfilter_syn5k0 + LP_FILTER_ORDER + i * SUBFR_SIZE,
 461                                                         SUBFR_SIZE);
 462             ff_adaptive_gain_control(&synth[i * SUBFR_SIZE],
 463                                      &synth[i * SUBFR_SIZE], energy,
 464                                      SUBFR_SIZE, 0.9, &ctx->postfilter_agc);
 465         }
 466
 467         memcpy(ctx->postfilter_syn5k0, ctx->postfilter_syn5k0 + frame_size,
 468                LP_FILTER_ORDER*sizeof(float));
 469     }
 470     memmove(ctx->excitation, excitation - PITCH_DELAY_MAX - L_INTERPOL,
 471            (PITCH_DELAY_MAX + L_INTERPOL) * sizeof(float));
 472
 473     ff_acelp_apply_order_2_transfer_function(out_data, synth,
 474                                              (const float[2]) {-1.99997   , 1.000000000},
 475                                              (const float[2]) {-1.93307352, 0.935891986},
 476                                              0.939805806,
 477                                              ctx->highpass_filt_mem,
 478                                              frame_size);
 479 }
 480
 481 static av_cold int sipr_decoder_init(AVCodecContext * avctx)
 482 {
 483     SiprContext *ctx = avctx->priv_data;
 484     int i;
 485
 486     switch (avctx->block_align) {
 487     case 20: ctx->mode = MODE_16k; break;
 488     case 19: ctx->mode = MODE_8k5; break;
 489     case 29: ctx->mode = MODE_6k5; break;
 490     case 37: ctx->mode = MODE_5k0; break;
 491     default:
 492         if      (avctx->bit_rate > 12200) ctx->mode = MODE_16k;
 493         else if (avctx->bit_rate > 7500 ) ctx->mode = MODE_8k5;
 494         else if (avctx->bit_rate > 5750 ) ctx->mode = MODE_6k5;
 495         else                              ctx->mode = MODE_5k0;
 496         av_log(avctx, AV_LOG_WARNING,
 497                "Invalid block_align: %d. Mode %s guessed based on bitrate: %"PRId64"\n",
 498                avctx->block_align, modes[ctx->mode].mode_name, avctx->bit_rate);
 499     }
 500
 501     av_log(avctx, AV_LOG_DEBUG, "Mode: %s\n", modes[ctx->mode].mode_name);
 502
 503     if (ctx->mode == MODE_16k) {
 504         ff_sipr_init_16k(ctx);
 505         ctx->decode_frame = ff_sipr_decode_frame_16k;
 506     } else {
 507         ctx->decode_frame = decode_frame;
 508     }
 509
 510     for (i = 0; i < LP_FILTER_ORDER; i++)
 511         ctx->lsp_history[i] = cos((i+1) * M_PI / (LP_FILTER_ORDER + 1));
 512
 513     for (i = 0; i < 4; i++)
 514         ctx->energy_history[i] = -14;
 515
 516     av_channel_layout_uninit(&avctx->ch_layout);
 517     avctx->ch_layout      = (AVChannelLayout)AV_CHANNEL_LAYOUT_MONO;
 518     avctx->sample_fmt     = AV_SAMPLE_FMT_FLT;
 519
 520     return 0;
 521 }
 522
 523 static int sipr_decode_frame(AVCodecContext *avctx, AVFrame *frame,
 524                              int *got_frame_ptr, AVPacket *avpkt)
 525 {
 526     SiprContext *ctx = avctx->priv_data;
 527     const uint8_t *buf=avpkt->data;
 528     SiprParameters parm;
 529     const SiprModeParam *mode_par = &modes[ctx->mode];
 530     GetBitContext gb;
 531     float *samples;
 532     int subframe_size = ctx->mode == MODE_16k ? L_SUBFR_16k : SUBFR_SIZE;
 533     int i, ret;
 534
 535     ctx->avctx = avctx;
 536     if (avpkt->size < (mode_par->bits_per_frame >> 3)) {
 537         av_log(avctx, AV_LOG_ERROR,
 538                "Error processing packet: packet size (%d) too small\n",
 539                avpkt->size);
 540         return AVERROR_INVALIDDATA;
 541     }
 542
 543     /* get output buffer */
 544     frame->nb_samples = mode_par->frames_per_packet * subframe_size *
 545                         mode_par->subframe_count;
 546     if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
 547         return ret;
 548     samples = (float *)frame->data[0];
 549
 550     init_get_bits(&gb, buf, mode_par->bits_per_frame);
 551
 552     for (i = 0; i < mode_par->frames_per_packet; i++) {
 553         decode_parameters(&parm, &gb, mode_par);
 554
 555         ctx->decode_frame(ctx, &parm, samples);
 556
 557         samples += subframe_size * mode_par->subframe_count;
 558     }
 559
 560     *got_frame_ptr = 1;
 561
 562     return mode_par->bits_per_frame >> 3;
 563 }
 564
 565 const FFCodec ff_sipr_decoder = {
 566     .p.name         = "sipr",
 567     .p.long_name    = NULL_IF_CONFIG_SMALL("RealAudio SIPR / ACELP.NET"),
 568     .p.type         = AVMEDIA_TYPE_AUDIO,
 569     .p.id           = AV_CODEC_ID_SIPR,
 570     .priv_data_size = sizeof(SiprContext),
 571     .init           = sipr_decoder_init,
 572     FF_CODEC_DECODE_CB(sipr_decode_frame),
 573     .p.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_CHANNEL_CONF,
 574     .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE,
 575 };